PLATE XLVn. 



PAGE 



Figs. 1-4. OsTEEA coMPEEssiKOSTEA Say 190 



1. Exterior of lower valve, 

 la. Interior of the same. 



lb. Lateral aspect of the same individua]. 



2, 3, 4. Exteriors of j^oung- upper valves. 



299 



